Fontes de nitrogênio, polpa de banana e ágar no desenvolvimento in vitro de plântulas de orquídea

Abstract

Two experiments were carried out in order to evaluate the effects of nitrogen sources, banana pulp and agar on Cattleya loddigesii seedlings development in vitro. In the first experiment were tested NH4NO3 at 0; 25; 50; 75 and 100% (330 mg L-1 formulation) and KNO3 0; 25; 50 and 100% (380 mg L-1 formulation) added to MS medium. The second experiment consisted of different agar concentrations (0; 2; 4; 6 and 8 g L-1), banana nanica pulp (0; 50; 100; 150 and 200 g L-1) in all the possible combinations added to Knudson C medium. After inoculation the plantlets were maintained in growth room with irradiancy around 35 μmol m-2 s-1, 25±1ºC temperature and 16-hour photoperiod for 90 days. The NH4NO3 formulation added to culture medium at 17,5 to 41,16% provides best development of Cattleya loddigesii plantlets based on plantlets fresh mass, number of roots, largest root length and aerial part length. Larger number of leaves was obtained at 100% of the original formulation of NH4NO3 and 50% of KNO3 in MS medium. The best results for in vitro multiplication of Cattleya loddigesii orchid seedlings occurred in liquid Knudson C medium with 128,42 g L-1 banana nanica pulp.